Lotus Elan

Rear Brake squealing. How to stop?

PostPost by: Elanman99 » Mon Jul 21, 2014 1:34 pm

For the last couple of years at least, the rear brakes on my S4 squeal in normal use, the noise disappears under heavy (or very light) braking and so far have been unable to solve the problem. Its not quite like B.O. but it does take some of the pleasure out of driving the car!

I put in new pads after putting chamfers on the leading edges but after 10 miles the noise is back again. Yesterday I made new pad retaining pins to replace the originals which were a pretty sloppy fit in the caliper holes so did allow the pad to float around.

The rear calipers never originally had any shims but I am now wondering whether to make some but thought I would ask here if anyone has used this approach and whether it worked?

The calipers and disks are in 'fair' condition with about a 3mm band of rust at the outer edges but the main wiped surface is not scored.

Ian
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PostPost by: Spyder fan » Mon Jul 21, 2014 1:56 pm

I stop mine squealing by using a proprietary spray on brake cleaner, Halfords do their own brand http://www.halfords.com/motoring/engine-oils-fluids/brake-clutch-fluid/halfords-brake-cleaner-500ml#tab3

I first started using this sort of stuff when the disc brakes on my push bike "squealed like a piggy", the very helpful guy at my local bicycle emporium recommended Muc Off spray cleaner and said the squealing was down to accumulated brake dust and or oil or fluid contamination of the disc face, the stuff was simplicity itself and just needed a good spray and a couple of heavy braking manoeuvres to totally clear the problemhttp://www.halfords.com/cycling/tools-maintenance/cleaning-lube/muc-off-disc-brake-cleaner-400ml

I would expect it to be exactly the same stuff as the Car specific version, it certainly smells the same (high solvent content).

I can't guarantee it will work for your car, but for ?5 it's certainly worth a go and won't do any harm, plus it will take just a few minutes to remove the wheels and have a jolly good spray up.
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PostPost by: theelanman » Mon Jul 21, 2014 2:02 pm

Ian
I'll see if I can get my hand on some anti squeal shims ......
they'll probably be over sized and require some artistry with the tin snips but should work......
ta
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PostPost by: Craven » Mon Jul 21, 2014 2:53 pm

Hi.
The latest idea/answer to brake squeal is a self-adhesive rubber type material stuck to the back of the pads, it supplied with some new pads, found these. http://www.partsforsaabs.com/product_in ... ts_id=3930
Ron.
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PostPost by: theelanman » Mon Jul 21, 2014 3:12 pm

Craven wrote:Hi.
The latest idea/answer to brake squeal is a self-adhesive rubber type material stuck to the back of the pads, it supplied with some new pads, found these. http://www.partsforsaabs.com/product_in ... ts_id=3930
Ron.

mmmmm....mintex..... :evil:
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PostPost by: Elanman99 » Mon Jul 21, 2014 5:38 pm

theelanman wrote:Ian
I'll see if I can get my hand on some anti squeal shims ......
they'll probably be over sized and require some artistry with the tin snips but should work......
ta
G


Thanks G

I'm not quite sure I know how shims work in the context of making brakes quieter. I know some shims have apertures positioned so that the piston applies more pressure on one part of the backplate, effectively 'tilting' the pad. Possibly it has the same or better effect as chamfering the leading edge of the pad.

If a shim was just a flat bit of metal the same size and shape as the backplate its hard to see how that could have any effect on squeal, if however it was curved instead of flat it would act as a spring and push the pad into continuous contact with the disk surface leading to premature pad wear.

Probably quite a complex subject this braking lark! I might try the brake cleaner suggested earlier.

Ian
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PostPost by: Quart Meg Miles » Mon Jul 21, 2014 10:31 pm

One assumes you are using Copperslip on the back of the pads...

The shims used on the front pads seem more to stop the pads rattling than to stop squeal and I'm never going to put a bit of rubber between the piston and pad, I like a hard pedal.
Meg

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PostPost by: p.faurie » Mon Jul 21, 2014 10:42 pm

Have you tried copper slip (anti seize compound) on the rear of the pads? I find it helps stop a lot of the noise,the other thing that may cause it,is the pad material, some harder type pads will cause this, I had a problem on my v8 esprit I fitted red or green stuff front pads(can't remember which),they squealed so much that when I had a look they had worn the grooves away on my new expensive discs.

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PostPost by: Spyder fan » Tue Jul 22, 2014 7:30 am

Probably quite a complex subject this braking lark! I might try the brake cleaner suggested earlier.

Ian


It's difficult to accept a simple solution when your expectations and advice from others are of a more complex nature. :mrgreen:
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PostPost by: theelanman » Tue Jul 22, 2014 7:41 am

Ian
most of the stuff we worked on/with was just a piece of aluminium (aluminum to the chaps of the left of the pond)
unless it was the high end stuff then these came as Kevlar weave...as specified by the likes of Brembo, AP etc etc
the steel back plate was preformed with 1 or more holes...the materials applied...pressed...cured and then finished.....this included the application of the shim which was generally ali plate painted with rubberized paint one side (outside) and the worlds most sticky glue on the other.....sticky side was applied to the steel backplate
between the compressibility of the wearing materials, the holes in the backplates and the shims the all conspired to eliminate screech......
cheers
G
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PostPost by: fatboyoz » Tue Jul 22, 2014 8:26 am

Ian,
I had the same problem, very embarassing. Whilst reading the following Yahoo Groups forum, I came across a drawing for rear brake shims. I had a set laser cut and with a little filing with a rat-tail file later they were fitted and have been noise free since.
https://groups.yahoo.com/neo/groups/vin ... s/messages
You will probably have to join the group to access the information. When in, select "files" then "Elan Stuff" and spool to the bottom.
Cheers,
Colin.


Elanman99 wrote:For the last couple of years at least, the rear brakes on my S4 squeal in normal use, the noise disappears under heavy (or very light) braking and so far have been unable to solve the problem. Its not quite like B.O. but it does take some of the pleasure out of driving the car!

I put in new pads after putting chamfers on the leading edges but after 10 miles the noise is back again. Yesterday I made new pad retaining pins to replace the originals which were a pretty sloppy fit in the caliper holes so did allow the pad to float around.

The rear calipers never originally had any shims but I am now wondering whether to make some but thought I would ask here if anyone has used this approach and whether it worked?

The calipers and disks are in 'fair' condition with about a 3mm band of rust at the outer edges but the main wiped surface is not scored.

Ian
'68 S4 DHC
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PostPost by: Elanman99 » Tue Jul 22, 2014 9:52 pm

After reading all the replies, I feel now that I have a good chance of curing the noise.

I have put copper grease on the edges of the pad but getting it on the backplate is difficult. With new pads, even with the piston fully retracted the rubber dirt seal wipes most of it off.

Most (all?) the shims I have come across have been steel or probably stainless steel, but using a softer metal seems like a good suggestion. I can easily make some shims out of aluminium using an old pad as a template so I don't really need a drawing. I will give it a try tomorrow.

Ian
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PostPost by: gus » Wed Jul 23, 2014 10:10 pm

i have never had a squeal problem, I am wondering if you have original [rusty] pistons. Rusty pistons do not retract correctly, which can lead to pad wear polishing and squeal.
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PostPost by: Elanman99 » Thu Jul 24, 2014 8:45 am

gus wrote:i have never had a squeal problem, I am wondering if you have original [rusty] pistons. Rusty pistons do not retract correctly, which can lead to pad wear polishing and squeal.


The pistons are replacements, not stainless but they are unmarked and the plating is undamaged so they retract correctly.

Aluminium shims are now fitted but the car is trapped by another car so not tested yet.

Ian
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